What Is Small Cell Lung Cancer

Lung cancer is the leading cause of cancer deaths among both men and women. However, it typically affects those of older ages. The average age of diagnosis is 70 years old. There are two major types of lung cancer: Small cell lung cancer and Non-small cell lung cancer. If a lung cancer has characteristics of both, it is called combined small cell/non-small cell cancer—but this is relatively uncommon.

SCLC, also known as oat cell carcinoma or small cell undifferentiated carcinoma, often grows quickly and spreads throughout areas of the body (metastasizes) prior to its detection. It often metastasizes to the brain, liver, and bones. It is the less common of the two. There are two main types of small cell lung cancer:

Small cell carcinoma

Combined small cell carcinoma

Non-small cell lung cancers (NSCLC) are more common than SCLC and tend to not spread throughout the body as quickly as SCLC. The three types of non-small cell lung cancers are:

Adenocarcinomas

Squamous cell carcinomas

Large cell carcinoma.

A third, very rare type of lung cancer has characteristics of both types and is referred to as mixed small cell/non-small cell lung cancer

It is also important to note that other cancers that originate in other sites of the body, such as breast or brain cancers, are not lung cancers, even when they spread or metastasize to the lungs. The cancer is still described by the area or organ of cancer origin.

Small cell lung cancer, or SCLC, is termed SCLC based on the kinds of cells found in the cancer and how the cells look when viewed under a microscope. These cancer cells have large nuclei (the part of the cell which contained DNA) and appear small in size.

SCLC accounts for 10-15% of all lung cancers in the United States. The American Cancer Society estimates in 2015 that 221,000 new lung cancer diagnoses will be made; and 158,040 people will die from lung cancer—comprising 24% of all cancer deaths.

What Causes Small Cell Lung Cancer

Almost all cases of SCLC are caused by cigarette smoking or exposure to second-hand smoke. It is rare in people who have never smoked It has also been linked to exposure to radon, asbestos, air pollution, and diesel exhaust.

According to the Mayo Clinic, smoking causes lung cancer by damaging the cells that line the lungs. As someone smokes, the lungs are exposed to cancer causing agents (carcinogens) in the smoke. These carcinogens damage the cells in the lungs, but the body is able to repair this damage. However, with continued smoking, the cells are eventually damaged beyond repair. As a result, the cells may begin to divide or replicate without control, which leads to cancer. This uncontrolled growth can be attributed to damage to normal regulatory mechanisms that limit how often DNA (the genetic information in the cell) replicates and allows cells to grow and replicate.

While most cases of SCLC are due to smoking or exposure to environmental toxins, not everyone who develops small cell lung cancer has a smoking or radon/asbestos exposure history, therefore genetics are also thought to be an important factor in the development of the disease. Specific genes within the DNA of cells have functions to regulate cell division. Genes involved in cell replication, or division, cellular growth, and cellular survival are called oncogenes, while those involved in limiting cell growth and division and induce cell death when necessary are called tumor suppressor genes (such as TP53 and RB1 genes). When cell DNA is damaged, these genes may be altered and the oncogenes are turned on and the tumor suppressor genes are turned off. As a result, there is uncontrollable cell growth and possible cancer. These changes to the DNA of cells are caused by the environment, but changes or mutations to DNA can also be inherited. If these mutations in the DNA correspond to genes that are involved with effective and correct cell replication, a person’s risk for developing lung cancers and other cancers may be increased.

Risk Factors For Small Cell Lung Cancer

Risk factors for developing small cell lung cancer include the following :

Smoking – cigarettes or cigar smoking. This is the strongest risk factor for lung cancer. The more you smoke and the longer you smoke, the higher your chance of developing the disease. Although it is suspected to increase your risk of lung cancer, it is currently not known if marijuana smoke increases your risk of lung cancer.

Second-hand smoke – even inhaling the smoke of those around you increases your risk of lung cancer. It is believed that exposure to second hand smoke increases your risk of lung cancer by 30%, and it is responsible for 7,000 deaths per year.

Radon – as a naturally occurring gas that results from the breakdown of uranium in soil, radon is the leading cause of lung cancer in those who do not smoke. Outdoors radon is not concentrated in the air we breathe. However, it may become concentrated indoors if a home is built around an area with abundant uranium and resulting radon. If you are concerned with the level of radon in your house, you can purchase a radon gas detection kit or hire personnel to test the amount in your home.

Asbestos – exposure to asbestos is also closely associated with the development of lung cancer. However, it typically leads to a type of lung cancer termed malignant melanoma. Common places of exposure include those who worked in mills, mining, textile plants, and shipyards.

Diagnosing Small Cell Lung Cancer

Lung cancers can be found by screening, like during a visit to your primary care physician, or by elective imaging studies, such as chest radiographs or computed tomography (CT) imaging. However, most lung cancers are discovered once they begin causing symptoms, such as shortness of breath, undesired weight loss, or pain.

At your doctor’s visit, your physician will begin by taking a detailed medical history and then perform a physical exam. If these lead him or her to believe you may have lung cancer, further tests will be ordered, which may include blood tests, imaging studies, or a lung biopsy.

A chest x-ray or radiograph will usually be the first study performed as it is convenient, cheap, and will reveal many lung cancers as a mass or shadow in the lungs. If the physician is suspicious for lung cancer, additional imaging studies will likely be obtained.

A CT scan also uses x-rays to generate an image, but it has several advantages compared to the chest x-ray. It will show the precise location, shape, and size of masses. In order to obtain even sharper images, some patients are asked to drink or receive IV contrast. This contrast makes some tissues appear brighter, which makes the images and the structures more apparent and easier to discern. Allergies to contrast medium may cause hives, flushing, shortness of breath, and low blood pressure. If you have had a reaction to contrast before, you should inform your physician. In addition to masses (such as cancers), it can show enlarged lymph nodes, which may have cancer cells. Many patients will have CT scans of the chest, as well as the abdomen to look for cancer spread, which may involve the liver, adrenal glands, or other internal organs. The CT scan may also involve the brain to look for cancer metastasis. A CT scan may also be used to obtain biopsies of masses or cancers what lie deep within or nearby other vital structures, which is termed CT guided needle biopsy.

A magnetic resonance imaging (MRI) study also provides detailed soft tissue “pictures.” As opposed to CT scans, which utilizes x-rays, MRIs use magnetic radiowaves to generate images. MRIs are particularly useful for imaging the brain and spinal cord. Gadolinium, a contrast, is often used to produce even better MRI images.

PET scans, also known as positron emission tomography, are especially useful to look for cancer spread. This study involves injecting a special radioactive sugar (flurodeoxyglucose, or FDP) into the vein. The amount of radioactivity is very low and will not cause you harm. After the injection, a special scanner will pickup areas in your body where the sugar has accumulated. As cancer cells are very active and require a great amount of energy (sugar), the FDP will concentrate in these areas. The PET scan does not produce extremely detailed images, but rather indicates spread of cancer throughout the body.

A similar test to the PET scan is the bone scan. During this procedure a specific substance that accumulates in rapidly changing areas of bone is injected in the vein. Areas of bone “turnover” such as areas of cancer show vividly on the scan.

A medical history, physical exam, and imaging studies may all suggest the diagnosis of lung cancer, but only the following tests can actually confirm a diagnosis of lung cancer:

Sputum cytology – cells are collected from lung secretions (usually obtained from deep coughs early in the morning) and then examined under the microscope

Thoracentesis – in the event that there is fluid around the lungs, which is termed a pleural effusion, doctors may insert a needle to drain the fluid to improve symptoms, such as shortness of breath because this fluid may impair the ability of air to enter and to exit the lungs. This fluid can then be examined for the presence of lung cancer cells under the microscope. Chemical tests can also be used to differentiate fluid with cancer cells from that without cancer cells.

Needle biopsy – to avoid a surgical incision, a doctor may wish to obtain cells from a suspicious mass via a needle biopsy. He or she can use a very thin, hollow needle and perform a fine needle aspiration (FNA). However a FNA risks not obtaining sufficient amount of tissue for a definitive diagnosis. To obtain more tissue, one can use a larger needle in a procedure termed a core biopsy. If the mass is in the outer portion of the lung, the physician may pass the needle through the chest wall skin to obtain the sample, which is termed a transthoracic needle biopsy. If the biopsy is performed while performing a bronchoscopy (discussed below), a transtracheal biopsy (through the trachea or windpipe) or transbronchial biopsy (through a large airway past the trachea) may be performed.

Bronchoscopy – during this procedure a long, lighted, flexible fiber optic tube is passed down the windpipe and into many smaller airways of the lungs to assess the delicate lining of the lungs for cancers. During a bronchoscopy, biopsies may be taken for later examination as well.

In order to assess the possible spread of cancer after a definitive diagnosis, a physician may perform an endobronchial ultrasound (which utilizes sound waves to look for masses or cancer spread around the large airways of the lungs) or endoscopic esophageal ultrasound (during which sound waves are used to assess cancer spread around the esophagus and areas of the lungs around the esophagus). Other methods, which are slightly more invasive, include a mediastinoscopy and mediastinotomy. During a mediastinoscopy, a small incision is made in the breast bone and a camera is passed down to look for cancer and suspicious lymph nodes in the area between the lungs. A mediastinotomy involves a slightly larger incision and allows more thorough investigation of lymph nodes deeper than those examined by mediastinoscopy. A step further is called a thorascopy, which is a surgery that allows visualization of the lungs and chest wall via a small camera inserted through the chest wall. If a larger incision is required, it may be termed a thoracotomy.

Nearby spread – hoarse voice from compression of the nerve supplying the vocal cords, shortness of breath from compression of the nerve that supplies the diaphragm, difficulty swallowing from involvement of the esophagus, swelling of the face and hands due to compression of a large vein in the neck (superior vena cava)

Prognosis

A standard way to discuss prognosis (or outlook) for a patient with any disease, can be accomplished by referring to survival rates. Survival rates are the percentage of patients who survive for any given time period. For example, a 5 year survival rate describes the percentage of people who are alive 5 years after diagnosis of a disease. Relative survival rates compare the survival of those with cancer to those without. It is important to note that the relative survival rates depend on the stage, or spread, of cancer.

The five year relative survival rates for small cell lung cancer are the following, depending on the stage, considering tumor size, lymph node involvement, and metastasis:

Stage 1 is 31%

Stage 2 is 19%

Stage 3 is 8%

Stage 4 is 2%.

As is quite apparent, small cell lung cancer is extremely deadly. Because it metastasizes so quickly, it is often spread throughout the body before it has been diagnosed.

Living With Small Cell Lung Cancer

According to the American Lung Association, people with cancer not only face physical challenges, but also mental and emotional challenges. It is important to understand your illness and treatment as it can make you feel more in control. Taking care of your emotional health is also vital. Family and friends can be an important source of support for you during this challenging time.

Screening

According to the US Preventative Services Task Force, it is recommended that adults aged 55-80 years with a 30 pack year smoking history and currently smoke or have quit in the last 15 years with low dose computed tomography (LDCT). Screening can be discontinued once a person has quit smoking for more than 15 years or develops a health problem that substantially limits life expectancy or the ability or the willingness to have curative lung surgery.

Prevention

The single most important and controllable method of preventing lung cancer is not smoking. By refraining from smoking, your risk of lung cancer decreases substantially. If you also avoid second-hand smoke, occupational exposures to known carcinogens, and live in an area with limited air pollution, you can severely decrease your risk of small cell lung cancer.

Unfortunately, if you inherit genes that increase your risk of lung cancer, this is considered a non-modifiable risk factor as you cannot change this aspect of your cancer risk.

Medication And Treatment

Small cell lung cancer is aggressive and tends to grow and to spread quickly. Because of the distant spread, or metastasis, surgery is usually not the ideal treatment as it is best for localized tumors.

The extent of disease within an individual patient is referred to as the stage of the cancer. The stage of the cancer, which is described on a scale from 1-4, with 1 being the least extensive and 4 being the most distantly spread. The stage of cancer is important in determining the best treatment for each patient and his or her prognosis.

Limited disease – limited small cell lung cancer is considered as cancer limited to only one lung and/or in the lymph nodes in the mediastinum (the region of the chest in between the two lungs). This disease classification correlates with stage I, II, or III. The majority of people are treated with chemotherapy and radiation targeted to the cancer consolidation in the chest/lungs. After this initial treatment, patients are then frequently treated with radiation to the brain in an attempt to prevent the development of brain metastases. The treatment goal for limited stage disease is cure. The most commonly used combination of chemotherapy medications is cisplatin (Platinol) and etoposide (VP-16, Vepesid). If patients do not tolerate the side effects from cisplatin, such as kidney injury, damage to nerves, and nausea , carboplatin (Paraplatin) may also be used. In very rare cases, the cancer may only reside in one lung, surgical excision may be considered. Chemotherapy and radiation may be offered after surgery as well.

Extensive disease–the majority of patients with small cell lung cancer have extensive stage disease at the time of diagnosis. By definition, extensive disease describes a cancer that has spread to the opposite side of the chest/lung or to more distant locations in the body. The most common sites of metastasis include the liver, adrenal glands, bones, and the brain. Patients with extensive disease are treated with chemotherapy, not surgery. The most common chemotherapy for these patients are cisplatin or carboplatin in combination with either etoposide or irinotecan (Camptosar). The goal of treatment for these patients is control of symptoms and to prolong life, but generally not cure. Preventative radiation to the brain to control metastasis is usually offered as well. Radiation to other parts of the body is also commonly performed for symptom control.

The side effects from these chemotherapy regimens can be extensive and may include a decrease in blood cell counts, fatigue, hair loss, nausea, vomiting, damage to nerves, hearing loss, diarrhea, mouth sores, decreased appetite, and damage to kidneys.

Radiation therapy may be utilized when patients have limited-stage small cell lung cancer. This treatment involves high energy x-rays focused on a specific site to kill cancer cells. The efficacy of radiation is cumulative, so multiple sessions of radiation are necessary for optimal treatment. Side-effects of radiation include fatigue, skin damage, swelling of the esophagus, and lung damage. As the brain is a common site for metastasis for patients with small cell lung cancer, preventative radiation treatment of the brain is common and efficacious for preventing brain metastases. This is termed prophylactic cranial irradiation, or PCI.

Finally, the importance of quitting smoking even after a diagnosis of lung cancer cannot be overemphasized. Patients respond better to treatment, and it is possible to develop a second cancer after treatment if smoking continues.

Complementary and Alternative Treatment

As the definitive treatment for small cell lung cancer remains medications and chemotherapy (and possibly surgery), alternative treatments for this condition should only be considered after surgical intervention.

Complementary medicine, which refers to interventions performed in addition to traditional or standard treatment, are numerous and may provide additional symptom relief and improved quality of life for many patients. According to the National Center for Complementary and Integrative Health, these include:

Acupuncture – is particularly effective in alleviating treatment-related nausea and vomiting in cancer patients. It may even help control cancer pain. Although complications from acupuncture are rare, it is important to ensure that the needles are properly sterilized. Many cancer patients have weakened immune systems and more prone to infections.

Ginger – may help to control nausea secondary to cancer chemotherapy, especially when used along with standard anti-nausea medications.

Massage therapy – may help to alleviate symptoms experienced by many cancer patients, such as pain, nausea, anxiety, and depression. However, the massage therapist should be careful to avoid deep or too rigorous massage prior to physician approval, especially directly over a tumor or around sensitive skin, which is common following radiation treatments.

Mindfulness-based Stress Reduction – as a type of meditation, mindfulness-based stress reduction can help cancer patients by relieving anxiety, stress, fatigue, and general mood and sleep disturbances. As a result, this can lead to an overall improvement in quality of life.

Yoga – preliminary studies suggest that yoga may improve anxiety, depression, and stress in patients with cancer. It may also alleviate fatigue in breast cancer patients. However, additional studies need to be completed for better evidence and conclusions.

Hypnosis, relaxation therapies, and biofeedback – various studies are currently assessing the benefits of these activities in cancer patients.

Herbal supplements – a 2008 review of research regarding herbal supplements and cancer concluded that the scientific evidence is limited and many clinical trials were not well designed. Furthermore, there are specific concerns regarding some herbal supplements in terms of medication interactions. Thus, any use of herbal medications should be discussed thoroughly with your physician.

When To Contact A Doctor

If you are experiencing any of the signs or symptoms of lung cancer (as described above), it is imperative you visit your primary care physician. Unless the symptoms are life-threatening, you can make an appointment within a reasonable time period and do not need to visit the emergency department.

Questions For A Doctor

When you go to see your doctor, it’s good to have a list of the questions you’d like to have answered. Take a moment to write down some of the things you want to know. Your questions for your doctor might include some of these: